This is a very minor glitch I found, not even sure if you could call it a glitch or not. Sorry if this has been submitted before. I searched and nothing came up. I just noticed this yesterday.
In Diamond and Pearl, Flying type moves have their discs colored a light shade of blue while Water type moves are a deeper blue. The HM Defog, a Flying move, is colored the darker blue of a Water move. I re-checked all of my other TMs and could not find an error similar to this.
Thanks for looking over my submission.
EDIT: I only checked this in Diamond and Pearl. I'm not sure if it remains in Platinum.